The Korean patent application KR 20010037026A discloses a method for establishing a recipe parameter in a wafer inspection process. The method is used to shorten the time taken to establish a recipe parameter and to reduce precision variation caused by the experience of an operator, therefore the recipe parameter of an inspection apparatus is stored in a library so that the recipe parameter is used in inspecting the wafer experiencing the same process. Optical or electrical recipe parameters vary according to the characteristic of the wafer to be inspected. The parameters are stored in a library. The characteristic of the wafer in inspection is inputted. Recipe parameters corresponding to the inputted characteristic of the wafer in inspection are read out from the library and automatically established.
The patent U.S. Pat. No. 6,959,251 B2 describes techniques for efficiently setting up inspection, metrology, and review systems for operating upon semiconductor wafers. Specifically, this involves setting up recipes that allows each system to accurately inspect semiconductor wafers. Pertinent information is gathered from these tools and presents the information to users in a way that reduces the time required to complete a recipe.
The international patent application WO 2009/148876 A1 describes a method and a system for generating information to be used for selecting values for parameter(s) of a detection algorithm. Without user intervention, a scan is performed of an area of a wafer using an inspection system. The method also includes selecting a portion of the defects from results of the scan based on a predetermined maximum number of total defects to be used for selecting values for the parameter(s) of the detection algorithm. The method further includes storing information, which can be used to select the values for the parameter(s) of the detection algorithm to be used for the inspection recipe without performing an additional scan of the wafer subsequent to the scan.
A method and a system for establishing a wafer testing recipe are disclosed in US 2009/290782 A1. A camera acquires images of a number of dice from a produced wafer. A software uses at least part of the images and composes a reference-image to be used as testing reference of a typical die image. Based on the reference-image single and/or repeatable elements of a die pattern are defined as a “zone of interest”. A Detection-Policy is determined for each of the zone of interest or for a group of similar zones of interest and determining the algorithm that will be used by each of the Detection-Policy. The parameters of each of the Detection-Policy's algorithms are determined. The Reporting-policy is determined by defining a set of specific names of defect classes that could be used during inspection of a specific lot of wafers. A creating a “wafer testing recipe” is created by integrating the testing reference of a typical die image, the defined zones of interest, the determined Detection-Policies, the parameters of the determined Detection-Policies' algorithms, the determined Reporting-Policies and the determined Inspection-Policies.
According to prior art a method or system the initial recipe is executed on one wafer. The user takes the results offline and judges the performance of the recipe by reviewing individual die images/results. Some good dies are rejected, which is overkill, and some bad dies are accepted, which is underkill. Purpose of the tuning is to minimize both overkill and underkill. The user modifies one or more parameters of the inspection recipe to his/her best knowledge and saves the new version of the recipe and re-inspects the entire wafer. The newly generated results are reviewed again one by one and the recipe is modified again if results are not yet satisfactory. This sequence is repeated multiple times until the overkill/underkill result is within specifications.
There are multiple drawbacks with the old method is that each tuning iteration takes a long time, the complete wafer has to be re-inspected, and the results have to be reviewed on individual die/defect level. The recipe changes have to be saved in another version of the recipe. The user is responsible for this recipe management.
Additionally, there is no good feedback on inspection results. The user has to keep track of dies of interest for review, because the recipe development is a manual action and result review will be limited to a set of dies that is manageable by the user. There is no reference available and the user has to keep track of the expected results for the dies of interest. Tuning can only be done on dies of 1 wafer at a time. Typically one wants to tune on dies of multiple wafers/lots. Improvements in the recipe for one wafer do not necessarily mean this is a recipe improvement for other wafers as well.
A lot of iterations are needed in order to come to a tuned recipe, because of the limited feedback and it is not easy to judge the impact of recipe changes. This makes that the number of iterations is large, adding to the time of coming to a good recipe.